Author Topic: manual fuel cut-off system?? (Read 9005 times)

haybayian · « **on:** May 04, 2008, 07:31:09 am »

As I am putting together the wiring harness in a VW AAZ powered homebuilt sportscar I cannot help but to wonder at the wisdom of the solenoid driven fuel cut-off VW device. I have two diesel engines in my boat both equiped with a manual shut-off lever. They work fine and nothing can go wrong really. On the other hand our German marvel relies on a solenoid and a 15 A fuse.....What were they thinking?

?

Does anyone know of a manual system, with a push/ pull cable and a knob?
Or do I have to fabricate my own?

Thanks,

Haybayian

jimfoo · « **Reply #1 on:** May 04, 2008, 07:51:25 am »

X2. Maybe you need to change your sig

haybayian · « **Reply #2 on:** May 04, 2008, 09:00:26 am »

Quote from: "libbybapa"

If, in fact, you have an automatic, then the pump is equipped with a manual shut-off lever. If the pump solenoid fails to not supplying fuel, then the plunger can be removed and the engine will run fine and the clutch dumping can be used to shut it off.

Andrew

Thank you for reacting to my post. I don't think that the magnetic valve in the VW is "wrong", I just think it is unnecessary and that a manual device would be "simpler". Now what is right/wrong, simple/complicated is a matter of perception, agreed. For someone with a perfectly running Jetta it would make little sense "fixing" what works. My own situation is different, I see this AAZ engine from the eyes of someone who is building an entire car from scratch..... this is the sort of adventure that triggers constructive criticism.

Your suggestion about the manual cutoff system to be found on automatic VWs is welcome, I will investigate.

Haybayian

jimfoo · « **Reply #3 on:** May 04, 2008, 09:51:03 am »

One thing about putting a separate manual shutoff (not the auto pump) is unless you can incorporate it into where the solenoid is, you are still going to be getting fuel for as long as the IP's vane pump can pump what is in the IP. Kind of like shutting the fuel off on a motorcycle, but having to run it a while if you want to drain the carb.

haybayian · « **Reply #4 on:** May 04, 2008, 10:14:46 am »

Quote from: "jimfoo"

One thing about putting a separate manual shutoff (not the auto pump) is unless you can incorporate it into where the solenoid is, you are still going to be getting fuel for as long as the IP's vane pump can pump what is in the IP. Kind of like shutting the fuel off on a motorcycle, but having to run it a while if you want to drain the carb.

Thanks,
I was sort of hoping that early 1.6 diesels VW might have a manual lever where the magnetic cut-off valve is now on the VE. I understand your point. I never considered shutting off the fuel upstream from the pump.

Haybayian

Vincent Waldon · « **Reply #5 on:** May 04, 2008, 11:01:58 am »

My guess is that the VW engineers designed the solenoid to be the easiest system to integrate into the ignition key... they were working hard to remove barriers to people moving from gas to diesel engines and there are many documented instances of design decisions made to remove objections to the diesel engine. In my mind a manual fuel control is not as driver friendly as the good old fashioned ignition. The glow plug light and cold start knob are confusing enough ??!! :wink:

haybayian · « **Reply #6 on:** May 04, 2008, 11:25:27 am »

Quote from: "Vincent Waldon"

My guess is that the VW engineers designed the solenoid to be the easiest system to integrate into the ignition key... they were working hard to remove barriers to people moving from gas to diesel engines and there are many documented instances of design decisions made to remove objections to the diesel engine. In my mind a manual fuel control is not as driver friendly as the good old fashioned ignition. The glow plug light and cold start knob are confusing enough ??!! :wink:

Thanks Vince,
Yes that was my guess too.
By throwing the question at this group I was assuming that most folks here are less focused on their rig's driver friendlyness and more on performance "mods" and that they would have an opinion. I guess in the big picture the cut-off system is not all that important.

Philippe.

jtanguay · « **Reply #7 on:** May 04, 2008, 11:48:36 am »

well why not integrate a system like on the mercs??? i believe those pumps use vacuum to stop. sure beats dumping the clutch all the time :lol:

Luckypabst · « **Reply #8 on:** May 04, 2008, 12:02:56 pm »

I'd like to have a manual shut off as well but I like having lots of knobs and shifters and whatnot. It would increase reliablity in a system that's not known for failure, so I guess that's a moot point. And it could save your butt in the middle of nowhere with a dead battery.

My Bosch distributor-type IP book mentions that there were cable operated fuel shut offs used in marine applications - theory being that you can still get home even with a complete electrical malfunction. Anyone seen a marine spec VE pump?

Chris

haybayian · « **Reply #9 on:** May 04, 2008, 12:27:00 pm »

Quote from: "Luckypabst"

I'd like to have a manual shut off as well but I like having lots of knobs and shifters and whatnot. It would increase reliablity in a system that's not known for failure, so I guess that's a moot point. And it could save your butt in the middle of nowhere with a dead battery.

My Bosch distributor-type IP book mentions that there were cable operated fuel shut offs used in marine applications - theory being that you can still get home even with a complete electrical malfunction. Anyone seen a marine spec VE pump?

Chris

I think Pathfinder was the name of the marinized diesel VW. Probably a 1.5 L. In a marine application you would still need a functional starter and battery. On the road (unless I am missing something) a good slope would fire her up.

Luckypabst · « **Reply #10 on:** May 04, 2008, 12:29:20 pm »

Yea, I was just repeating what I read. Maybe they meant for times when the engine is already running and the electrics fail? Not easy to bump start a boat...

Chris

burnt_servo · « **Reply #11 on:** May 04, 2008, 03:34:07 pm »

the dodge cummins with a ve pump also have a lever for manual pump shut off .

the vw's don't have this lever .

to make a shut off lever for a vw would require a person to have a very good knowledge of the ve pump and the ability to make a "hybrid " pump , combining vw parts , and a pump with a manual shut off lever .

this would be expensive and overly complicated to avoid what problem

the posibility of solinoid failure on the injection pump ?
i've never seen the solinoid fail in any vw .

Baxter · « **Reply #12 on:** May 04, 2008, 04:29:47 pm »

....plus the solenoid fails safe anyway.
It fails, it stops.
Simple.

Methanolab · « **Reply #13 on:** September 24, 2008, 10:41:50 am »

Has anyone made any progress on this? I was thinking about it because I would like to be able to start without electricity in an emergency. If you think about it one of the great benefits to this motor is that it can run completely mechanically. I thought that was the root of the original post, as in "why would VW make such a great mechanical motor and then 'ruin' it with an electrical keystone?"
Has anyone ever taken the plunger out of the solenoid like Andrew said you can? If that is quick and easy to do in an emergency I would be satisfied.

edit:
Ah I found this killer pump rebuild thread Andrew put up on VWdiesel parts:
http://www.vwdieselparts.com/forum/viewtopic.php?t=6694 Lots of pictures, fifth one from the bottom. The plunger looks like it falls right out. Yea?

jtanguay · « **Reply #14 on:** September 24, 2008, 10:45:31 am »

you could make it run like the mercedes do... they use vacuum as the fuel shut off.

i think the solenoid is a good idea.. it's proven technology that is simple, yet effective. but i too would like to have a completely mechanical engine

Author Topic: manual fuel cut-off system?? (Read 9005 times)

Baxter